Question 1

How is the pressure generally at the centre of a cyclone?

Accepted Answer

Low A cyclone is an atmospheric system organised around a centre of relatively low pressure. Air tends to move horizontally toward this centre and rise, especially when conditions support convergence and uplift. Rising air can produce cloud, rain, and unsettled weather. The centre is not pressureless; it simply has lower pressure than the surrounding region, so option A is correct.

Question 2

How is surface pressure generally distributed in an anticyclone?

Accepted Answer

High An anticyclone is a weather system centred on relatively high surface pressure. Air generally descends near the centre and diverges outward at the surface. Descending air suppresses cloud development, so anticyclones are often associated with stable, dry, and comparatively clear weather. The pressure is not pressureless or low; therefore, high pressure in option B is correct.

Question 3

What is an air mass?

Accepted Answer

A large body of air with relatively uniform temperature and humidity An air mass is a large body of tropospheric air that develops fairly uniform temperature and moisture characteristics over a broad source region. Its properties are acquired from the surface beneath it, such as a warm ocean, cold land, or snow-covered area. When it moves away, it influences the weather of the regions it crosses.

Question 4

The properties of an air mass mainly depend on what?

Accepted Answer

The nature of its source region An air mass acquires its temperature and moisture characteristics from the source region where it remains for a considerable period. A continental source usually makes air relatively dry, whereas a maritime source makes it moist. The source region’s latitude also affects temperature, so option B is the only scientifically relevant choice.

Question 5

What is a front?

Accepted Answer

The boundary between two different air masses A front is a transition zone or boundary separating two air masses with different temperatures, humidity, or density. Because the air masses interact along this zone, fronts often produce cloud development, precipitation, and noticeable changes in wind direction or temperature. Thus, option C gives the correct definition; a front is not simply a calm area or a sea-wave measurement.

Question 6

When does a cold front form?

Accepted Answer

When cold air advances and forces warm air upward A cold front forms when a colder, denser air mass advances into a region occupied by warmer air. The cold air wedges beneath the warm air and forces it to rise. This uplift may produce clouds, showers, thunderstorms, and a relatively sharp weather change. Option D correctly describes the advancing cold air and the resulting uplift of warm air.

Question 7

Which air advances in a warm front?

Accepted Answer

Warm air A warm front develops when a warm air mass advances toward and gradually rises over a retreating colder air mass. Because warm air is generally less dense, it rises along a gentle slope above the cold air rather than sharply displacing it. This commonly produces layered clouds and widespread, steady precipitation. Therefore, warm air is the advancing air and option A is correct.

Question 8

A cyclone is generally associated with which pressure area?

Accepted Answer

A low-pressure area A cyclone is a large-scale system organized around a low-pressure centre. Surface winds generally converge toward the centre and rise, often producing cloud, rain, and unsettled weather. The exact rotation depends on the hemisphere because of the Coriolis effect, but the low-pressure association remains fundamental. Therefore, option B is correct; high pressure is characteristic of an anticyclone.

Question 9

An anticyclone is generally related to which pressure area?

Accepted Answer

A high-pressure area An anticyclone is a high-pressure system in which air generally subsides near the centre and diverges outward at the surface. Descending air suppresses cloud formation, so anticyclones are often linked with stable, dry, and relatively clear weather, although local conditions can modify this outcome. Option C is therefore correct, while low pressure is associated with cyclones.

Question 10

What is the main feature of a maritime air mass?

Accepted Answer

It generally contains abundant moisture A maritime air mass forms over an ocean or another large water body. Continuous contact with the water surface allows evaporation to add substantial water vapour, so the air mass is generally humid. Its temperature may be warm or cold depending on latitude and season; therefore, “maritime” primarily indicates a moist source, not necessarily an icy or warm one. Option D is correct.

Question 11

How is a continental air mass generally?

Accepted Answer

Less humid or dry A continental air mass develops over a large land surface. Since land usually supplies much less water vapour than an ocean, the air mass is generally dry or has low humidity. Its exact temperature depends on whether it forms in a tropical or polar region, but its continental character is identified mainly by limited moisture.

Question 12

A tropical air mass is generally of which type?

Accepted Answer

Warm A tropical air mass forms in or near the tropics, where the Sun’s rays are relatively direct and average temperatures are high. Therefore, its defining thermal characteristic is warmth. The amount of moisture may vary according to whether it develops over land or water, but tropical specifically refers to warm temperature conditions.

Question 13

What is the general feature of a polar air mass?

Accepted Answer

Cold A polar air mass forms over or near high-latitude polar regions, where surface temperatures are low and the air becomes cold. Its moisture content can differ depending on whether it forms over land or ocean, so the most general and reliable characteristic given here is low temperature, represented by option C.

Question 14

When does a stationary front form?

Accepted Answer

When the boundary between two air masses remains almost stationary A stationary front develops when two contrasting air masses meet but neither one advances enough to replace the other. Their boundary therefore remains nearly fixed, although winds may blow parallel to it. Because clouds, lifting, and precipitation can persist along the boundary, such fronts may produce prolonged unsettled weather.

Question 15

Why does weather change quickly near fronts?

Accepted Answer

Because air masses with different properties meet there A front is the transition zone between air masses with different temperatures, humidity, densities, and sometimes wind directions. As these air masses meet, one may rise over the other, producing cloud development, precipitation, wind shifts, and temperature changes. These interacting processes make weather near a front change rapidly.

Question 16

What is the general behaviour of surface air in a cyclone?

Accepted Answer

Converging inward A cyclone is a low-pressure system. At the surface, air moves from the surrounding higher-pressure areas toward the central low-pressure region, so it converges inward. This converging air is forced to rise near the centre, often producing clouds, rain, and other unsettled weather. The exact rotation direction depends on the hemisphere.

Question 17

In the Northern Hemisphere cyclonic winds generally rotate in which direction?

Accepted Answer

Anticlockwise In the Northern Hemisphere, air moving toward a cyclone’s low-pressure centre is deflected to the right by the Coriolis effect. This deflection produces an anticlockwise circulation around the low-pressure centre. Friction and local geography can modify the flow, but the general hemispheric pattern is anticlockwise rotation.

Question 18

In the Southern Hemisphere cyclonic winds generally rotate in which direction?

Accepted Answer

Clockwise In the Southern Hemisphere, the Coriolis effect deflects moving air to the left. Air flowing toward a cyclone’s low-pressure centre therefore curves into a clockwise circulation. This is opposite to the anticlockwise rotation of Northern Hemisphere cyclones. The question refers to the general pattern, not small local disturbances or frictional variations.

Question 19

Where do tropical cyclones generally form?

Accepted Answer

Over warm tropical oceans Tropical cyclones generally form over warm tropical oceans because they need a large supply of heat and moisture. Warm seawater causes strong evaporation, and the moist air releases latent heat as it rises and condenses. This energy helps the low-pressure circulation intensify. They usually weaken over land or cold water.

Question 20

What is the pressure at the centre of a cyclone?

Accepted Answer

Low The centre of a cyclone is characterized by relatively low atmospheric pressure compared with the surrounding area. Air at the surface moves toward this pressure minimum and converges, while rising motion near the centre can produce clouds and precipitation. Cyclone does not mean zero pressure; it means a well-defined low-pressure circulation.

Question 21

Which weather is generally associated with a cyclone?

Accepted Answer

Clouds, rainfall, and strong winds A cyclone is a low-pressure system in which air generally converges and rises. Rising air cools and may condense, producing extensive cloud cover and rainfall. The pressure gradient can also generate strong winds around the system. Therefore, cloudy, rainy, and windy weather is the most typical association, although the exact conditions depend on the cyclone’s strength, location, and moisture supply.

Question 22

How is the weather generally in an anticyclone?

Accepted Answer

Clear and stable An anticyclone is a high-pressure system with descending air. As air sinks, it becomes warmer and relatively drier, reducing condensation and cloud development. Winds are usually lighter and weather is often settled, clear, and stable. Fog or low cloud can occasionally occur near the surface, so the word “generally” is important; nevertheless, clear and stable weather is the best answer.

Question 23

What should a source region be like for air mass formation?

Accepted Answer

Large and uniform in character An air mass develops when air remains over a source region long enough to acquire the region’s temperature and moisture characteristics. A large, fairly uniform surface allows these properties to become similar throughout the air. Oceans, broad deserts, snowfields, and extensive plains can therefore act as source regions. Small or highly varied terrain does not provide uniform conditions for air-mass formation.

Question 24

A moist air mass is more likely to form over which source region?

Accepted Answer

Ocean Air that remains over an ocean receives a continuous supply of water vapour through evaporation from the sea surface. It can therefore develop high humidity and become a maritime or oceanic air mass. Deserts and other dry continental surfaces usually add much less moisture to the air. Thus, an ocean is the most suitable source region for a moist air mass, provided the air remains there long enough.

Question 25

Why does warm air rise at a front?

Accepted Answer

Because warm air is lighter Heating makes air expand. For the same amount of air, expansion lowers its density, so warm air becomes more buoyant than the surrounding cold air and tends to rise. At a front, the denser cold air often stays near the ground while warm air is lifted above it. Rising warm air may cool to its dew point, causing cloud formation and sometimes precipitation.

Air masses, fronts, and cyclones

Practice questions

01 How is the pressure generally at the centre of a cyclone?

02 How is surface pressure generally distributed in an anticyclone?

03 What is an air mass?

04 The properties of an air mass mainly depend on what?

05 What is a front?

06 When does a cold front form?

07 Which air advances in a warm front?

08 A cyclone is generally associated with which pressure area?

09 An anticyclone is generally related to which pressure area?

10 What is the main feature of a maritime air mass?

11 How is a continental air mass generally?

12 A tropical air mass is generally of which type?

13 What is the general feature of a polar air mass?

14 When does a stationary front form?

15 Why does weather change quickly near fronts?

16 What is the general behaviour of surface air in a cyclone?

17 In the Northern Hemisphere cyclonic winds generally rotate in which direction?

18 In the Southern Hemisphere cyclonic winds generally rotate in which direction?

19 Where do tropical cyclones generally form?

20 What is the pressure at the centre of a cyclone?

21 Which weather is generally associated with a cyclone?

22 How is the weather generally in an anticyclone?

23 What should a source region be like for air mass formation?

24 A moist air mass is more likely to form over which source region?

25 Why does warm air rise at a front?

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